Chapter 2
Using the Module
2-14
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To convert module readings to strain use the following equation:
Full-Bridge Type II
This section provides information for the full-bridge type II strain-gage configuration. The
full-bridge type II only measures bending strain. Figure 2-13 shows how to position
strain-gage resistors in a bending configuration. Figure 2-14 shows the full-bridge type II
circuit wiring diagram.
Figure 2-13.
Full-Bridge Type II Rejecting Axial and Measuring Bending Strain
A full-bridge type II configuration has the following characteristics:
•
Four active strain-gage elements. Two are mounted in the direction of bending strain with
one on one side of the strain specimen (top) and the other on the opposite side (bottom).
The other two act together as a Poisson gage and are mounted transverse (perpendicular)
to the principal axis of strain with one on one side of the strain specimen (top) and the
other on the opposite side (bottom).
•
Rejects axial strain.
•
Sensitivity ~ 1.3
μ
V/V per
με
, for GF = 2.0.
strain
(
ε )
V
r
–
GF
--------
=
R
4
(+ )
(– )
(– )
(+ )
R
1
R
2
R
3
R
3
R
2
R
1
R
4
Rejects Axial
Measures Bending
